Currently, liquid solvents such as photoresist fluid is used ubiquitously in the production of semiconductor devices. Photoresist fluids, including positive and negative photoresist fluids, are used in processes such as photolithography and photoengraving to create coating patterns on the surface of a semiconductor wafer. High purity photoresist fluids are desired so that the semiconductor devices are free from contaminants, impurities, and the like that could hamper or destroy the functioning of the semiconductor devices. At this time, the photoresist fluids are typically subjected to filtration to reduce or eliminate contaminants that might be in the photoresist fluids received from manufacturers thereof.
The photoresist fluid filtration is often conducted by flowing the photoresist fluid through a filter cartridge which includes a nylon or polytetrafluoroethylene filter. As received from a manufacturer, the filtration cartridge includes void space through which liquid solvent, such as photoresist fluid, flows over the solid filter surface. Currently, liquid solvent is flowed through the filter cartridge to fill the void spaces through the filter until bubbles no longer exit the filter cartridge. This technique fully wets out the filter and also serves to flush the filter of any unwanted contaminants. Thus, the filter is flushed and wetted to rinse the filter membrane, reduce leachables and presence of any handling or installation residue in the downstream system, and to wet the filter prior to a pre-use integrity test. The reduction of leachables and downstream particles are intrinsic benefits of a liquid solvent flush to wet for integrity testing and do not require separate actions. However, the liquid solvent exiting the filter is discarded, producing increased costs than would otherwise be desirable. The inventors herein recognized that residual gas in the filter cartridge as received from a manufacturer dissolves more slowly into the liquid solvent that is otherwise desirable, resulting in inefficiency and loss of liquid solvent.
For example, FIG. 1 shows a prior art system used in a flushing procedure currently used in industry to wet a filter cartridge. In this set up, the liquid solvent, such as a photoresist fluid, wets the filter, flushes out air bubbles, and also flushes out leachable contaminants left from the manufacturing process used to make the filter. The liquid solvent is typically flushed until no bubbles appear in the liquid solvent that exits the filter cartridge. The liquid solvent that is used to flush the filter cartridge is discarded.
The inventors herein recognize that the discarded photoresist fluid is wasteful and adds cost to the manufacture of semiconductor devices. The inventors sought to provide a solution for this problem.